Giro is definitely the hardest when the road heads uphill, no doubt about that. Something that I think is often overlooked though is how tough the flat stages are in the Tour. All the Dutch and Belgian riders stringing it out on the flats of northern/western France, riding in the wind, and the constant fight for GC riders just to stay upright and not lose their position - it's usually pretty draining. But this year I'm not sure the Tour will have so much of that because the races starts in the south - it will probably settle down quicker.
Regardless of difficulty, the Giro is the one I'm most looking forward to (going to head out there for the first few stages too!). The Tour is still main event for a lot of big names but in the last 10 years the Giro has really narrowed the gap - the idea of a non-Italian defending Tour champ deciding to focus on the Giro a year later would have been unthinkable in past years.
Last edited by Cult Classics; 02-03-13 at 10:39.